The present invention generally relates to the field of semiconductors, and more particularly relates to forming semiconductor fins using mandrels and spacers having different etching characteristics.
As integrated circuits continue to scale downward in size, fin field effect transistors (finFETs) are becoming increasingly attractive to be used in smaller nodes, e.g., the 22 nm node and beyond. One problem that is associated with forming semiconductor fins at tight pitch is that the process window for cutting of unwanted semiconductor fins is quite narrow. More specifically, the space available between fins at a tight pitch decreases the process window for placement of a fin cut mask edge in between fins. As the pitch of the semiconductor fins decreases, it becomes difficult to remove unwanted semiconductor fins without adversely affecting adjacent device fins due to the process variation and small process margin of lithographic processes.